How we measure
A number without a method is a guess with good typography. Every figure we publish carries a tag that says what kind of number it is.
Three kinds of number
Measured
Taken from the real device on our bench, with the method written next to it: the device, the conditions, the instrument and the date.
Model
Calculated from datasheets and stated assumptions, to show the shape of a problem. The scope on our home page is a model, and says so.
Method note pending
A number we have recorded but not yet written up. We show it with this tag rather than hide it or pass it off as measured.
What a method note holds
Four fields, enough for someone else to repeat the measurement and get the same answer.
Method note
Example layout
- Device
- Which board and revision, with what attached
- Conditions
- Supply voltage, temperature, signal strength, number of cycles
- Instrument
- What measured it, at what range and sample rate
- Date
- When it was measured, so later changes can be traced
Measuring current
- Measure the whole cycle, not one moment of it. A node's average includes every wake and every sleep.
- Sleep and wake need different ranges. Microamps and radio bursts of hundreds of milliamps are measured in a way that sees both.
- Average many cycles. One wake can be lucky with the Wi-Fi; fifty usually are not.
- Measure the real board, with its real sensors attached and its real supply.
- Write down the supply voltage and the temperature. Both move the result.
What we won’t write
- Grades we can't test, such as “military-grade” or “industrial-grade”.
- A live dashboard that is really a simulation. If it's a model, it is labelled as one.
- An accuracy figure without the data it was measured on.
- A battery life without its interval, its battery and its temperature.
Found a number on this site without a tag? Tell us at contact@buildiotlabs.com and we’ll tag it or take it down. Our tools show their working for the same reason.